A cross-shaped insert-based unit connection joint of a steel structure modular building

Abstract

The application discloses a kind of steel structure module building's unit connecting node based on cross-shaped insert, including upper module assembly, lower module assembly, vertical connecting plate, lower column top plate, upper column bottom plate, high-strength bolt and node plate with cross-shaped insert.The upper module assembly and lower module assembly are respectively included 4 module units, the bottom of each module column in the upper module assembly is fixed with upper column bottom plate, and the top of each module column in the lower module assembly is fixed with lower column top plate;Wherein upper column bottom plate and lower column top plate are all provided with cross-shaped hole, and bolt mounting hole is provided outside cross-shaped hole, cross-shaped hole is used to install node plate with cross-shaped insert, improve the strength of node core area, node plate with cross-shaped insert is prefabricated in factory;Wherein bolt mounting hole is provided on cross-shaped insert connecting plate.The application avoids on-site welding, can guarantee node construction quality, and structure is simple, force transmission is clear, mechanical property is good, node core area is high in strength, and is convenient for installation.

Description

Technical Field

[0001] This invention belongs to the field of steel structure modular building in civil engineering, specifically referring to a unit connection node based on a cross-shaped plug for connecting steel structure modular columns. Background Technology

[0002] Since the beginning of the 21st century, modular structures have been widely used due to their advantages such as high production efficiency, short construction cycle, and recyclability. Module connection nodes are one of the key technologies restricting the development of prefabricated buildings towards multi-story and high-rise buildings; the reliability of the connection nodes between modular columns directly affects the overall performance of the structure. Although some research has been conducted on inter-module nodes, many problems remain regarding mechanical properties, construction and engineering, and research level. There is a failure to adequately balance the conflict between efficient on-site assembly and good load-bearing performance of inter-module connection nodes, specifically manifested in the following aspects:

[0003] 1. Low on-site assembly efficiency. Complex node structures and extensive on-site welding are required.

[0004] 2. Insufficient bending stiffness at joints. Traditional steel structure design methods often overlook the impact of adjacent columns between modules on the load-bearing performance of the joints;

[0005] 3. Low joint strength. Some joints sacrifice plate thickness and increase cross-section to achieve better mechanical properties, which is not economical.

[0006] In summary, there is a lack of modular steel structure building module connection node designs that can be widely applied in practical engineering. Reviewing the current research status of module connection nodes both domestically and internationally, it is evident that existing research is limited to addressing only one or some aspects of on-site assembly, node stress performance, and overall structural stress, failing to comprehensively consider all characteristics. This paper focuses on the module connection nodes, which have the greatest impact on the overall performance of modular buildings and are the subject of the most concentrated scholarly attention. In particular, it introduces typical construction forms and research status of the central nodes between modules that meet the "eight columns and sixteen beams" characteristic, and analyzes their advantages and disadvantages.

[0007] In their paper "Experimental study of an innovative modular steel building connection," Chen Zhihua et al. proposed a cast steel insert-through bolt beam-beam connection node. However, because the upper and lower modules are connected only by through bolts at the ends of the module beams that connect to the module columns, gaps appear between the upper and lower module columns under lateral forces, failing to effectively transfer tensile forces. Furthermore, the through bolts restrict the beam cross-section to box-section beams, making it less economical compared to cold-formed thin-walled steel beams.

[0008] In their paper "Research on Novel Connection Nodes and Structural Mechanical Properties of Modular Steel Frames," Liu Mingyang et al. proposed an inner sleeve welded node. However, the extensive use of welded nodes does not align well with the advantages of prefabricated buildings, such as convenient and quick construction and energy efficiency. Furthermore, the large gaps between the modular columns hinder the transmission of horizontal forces.

[0009] In their paper "Research on the Mechanical Properties of New Joints in Steel Structure Integrated Modular Buildings," Deng Enfeng et al. proposed a bolt-sealing plate joint. To compensate for the section weakening caused by construction openings when bolting the column ends, a welded sealing plate was used for reinforcement. Although the welded sealing plate can effectively resist the formation of the joint core area and ensure the joint's load-bearing capacity and ductility, the sealing plate is relatively thick, and welding increases the workload of on-site construction. Furthermore, this joint is only suitable for edge joints and not for intermediate joints. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a unit connection node for steel structure modular buildings based on a cross-shaped plug. This node has excellent mechanical properties, simple construction, convenient installation, high strength, clear force transmission, and wide applicability.

[0011] This node comprises an upper module assembly, a lower module assembly, a vertical connecting plate, a lower column top plate, an upper column bottom plate, high-strength bolts, and a node plate with cross-shaped inserts. Both the upper and lower module assemblies consist of four module units, which are prefabricated in the factory. Each module unit includes a module column and a module beam connected to the module column. The module beams connected to the module column are welded in the factory to ensure the welding process. Each module column in the upper module assembly has an upper column bottom plate fixed to its bottom, and each module column in the lower module assembly has a lower column top plate fixed to its top. Both the upper and lower column bottom plates have cross-shaped holes, and bolt mounting holes are located on the outer side of these cross-shaped holes. These holes are used to install the node plate with cross-shaped inserts, improving the strength of the node's core area. The node plate of the character-shaped plug is prefabricated in the factory. This includes welding four cross-shaped plugs onto a cross-shaped plug connecting plate to form a node plate with cross-shaped plugs. The cross-shaped plug connecting plate has bolt mounting holes, and the upper and lower ends of the cross-shaped plugs are used to insert into the cross-shaped holes on the upper column base plate and the lower column top plate, respectively. On-site, the four modular columns in both the upper and lower module components are fixed together by vertical connecting plates to form a combined column, creating a combined cross-section that shares the load, making it safer and more reliable. On-site, the upper and lower module components are connected by high-strength bolts, avoiding on-site welding and simplifying installation. This invention avoids on-site welding, ensures node construction quality, has a simple structure, clear force transmission, good mechanical properties, high strength in the node core area, and is easy to install.

[0012] To achieve the purpose of this invention, this invention provides a unit connection node for a steel structure modular building based on a cross-shaped plug, comprising an upper module assembly, a lower module assembly, a vertical connecting plate, a lower column top plate, an upper column bottom plate, high-strength bolts, and a node plate with a cross-shaped plug.

[0013] Both the upper and lower module components include four module units. Each module unit includes a module column and a module beam connected to the module column. Each module column in the upper and lower module components is enclosed and fixed by vertical connecting plates to form a composite column.

[0014] Each module column in the upper module assembly is fixed with an upper column base plate at its bottom, and each module column in the lower module assembly is fixed with a lower column top plate at its top. Both the upper column base plate and the lower column top plate are provided with cross-shaped holes, and bolt mounting holes are provided on the outside of the cross-shaped holes.

[0015] The node plate with cross-shaped inserts includes a cross-shaped insert connecting plate and a cross-shaped insert fixed on the cross-shaped insert connecting plate. The cross-shaped insert connecting plate has bolt mounting holes. The upper and lower ends of the cross-shaped insert are used to insert into the cross-shaped holes on the upper column base plate and the lower column top plate, respectively. The high-strength bolts are matched with the bolt mounting holes on the upper column base plate, the lower column top plate, and the cross-shaped insert connecting plate.

[0016] Furthermore, it also includes multiple single-sided bolts, in which the vertical connecting plate in the upper module assembly and the lower module assembly is connected and fixed to the module column by single-sided bolts.

[0017] Furthermore, the modular unit is prefabricated in the factory and includes: modular columns, modular beams connected to the modular columns, lower column top plates, and upper column bottom plates. In the factory, modular beams are welded to the adjacent two sides of the modular columns. At the same time, the bottom of each modular column in the upper modular assembly is fixed with an upper column bottom plate, and the top of each modular column in the lower modular assembly is fixed with a lower column top plate. Bolt mounting holes are reserved 2-5cm above or below the welding part of the modular column and the modular beam for matching the bolt mounting holes on the vertical connecting plate.

[0018] Furthermore, the thickness of the column end base plate and column end top plate is greater than 8mm, and they are provided with cross-shaped holes to match the cross-shaped inserts.

[0019] Furthermore, the node plate with cross-shaped inserts is prefabricated in the factory and includes: cross-shaped inserts and cross-shaped insert connecting plates. In the factory, the cross-shaped inserts and cross-shaped insert connecting plates are welded together to form the node plate with cross-shaped inserts. The cross-shaped insert connecting plates are provided with bolt mounting holes, and the ends of the cross-shaped inserts are chamfered for installation.

[0020] Furthermore, the upper and lower ends of the cross-shaped plug are inserted into the cross-shaped holes of the upper column base plate and the lower column top plate, respectively, and the cross-shaped plug serves to strengthen the core area of ​​the node.

[0021] Furthermore, on-site, the four modular columns in the upper and lower modular components are all enclosed and fixed by vertical connecting plates to form combined columns, forming a combined cross section to share the load, which is safer and more reliable.

[0022] Furthermore, the vertical connecting plate uses single-sided bolts to achieve single-sided installation and single-sided tightening; and the thickness of the vertical connecting plate is greater than 8mm.

[0023] Furthermore, on-site, the upper and lower module components are connected as a whole using high-strength bolts through the bolt mounting holes of the upper column base plate, lower column top plate, and node plate with cross-shaped inserts, making the connection more reliable and simpler.

[0024] Furthermore, the bolt mounting holes for the lower column top plate and the upper column bottom plate are standard holes or oblong holes to facilitate installation, and high-strength bolts are selected.

[0025] Furthermore, the upper module components, lower module components, node plates with cross-shaped plugs, lower column top plates, upper column bottom plates, and vertical connecting plates are all made of low-alloy high-strength structural steel Q355 steel; the high-strength bolts and single-sided bolts are grade 10.9 bolts made of 20MnTiB.

[0026] Compared with the prior art, the present invention has at least the following advantages and effects:

[0027] (1) Simple construction and high quality. All modular units are prefabricated in the factory, avoiding on-site welding, greatly improving construction efficiency and ensuring construction quality. When splicing nodes on site, only bolts need to be installed, without welding, making construction convenient and quick. In addition, beam and column welding is carried out in the factory to ensure welding process. At the same time, workers can easily repair and replace bolts to ensure the service life of nodes.

[0028] (2) Good mechanical properties and more reliable connection. The load-bearing modular steel structure building has a clear force transmission path and diverse modular specifications; at the same time, the use of vertical connecting plates and single-sided bolts makes multiple modular columns form a combined modular column, which jointly participates in the coordination of deformation and stress, with large node stiffness and small inter-story displacement, which strengthens the transmission of horizontal loads and avoids the gaps between bundled modular columns from affecting the transmission of horizontal loads.

[0029] (3) High strength. The node plate with cross-shaped plug, the top plate of the lower column end, the bottom plate of the upper column end, and the high-strength bolts improve the vertical connection between the module units, so that the node has sufficient rigidity and reliable connection, clear force transmission, and good stability. This invention does not sacrifice the thickness of the plate section or increase the cross section to obtain better mechanical properties. Instead, it uses cross-shaped connectors to strengthen the core area of ​​the node through cross-shaped plugs, thereby improving the load-bearing capacity of the node and meeting the requirement of "strong node, weak component".

[0030] (4) The connecting components are simple and convenient, can be standardized, and are easy to mass-produce. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of a steel structure modular building based on a cross-shaped plug-in unit connection node provided in an embodiment of the present invention.

[0032] Figure 2 This is an exploded view of the unit connection node based on a cross-shaped plug-in in a steel structure modular building according to an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of a node board structure with a cross-shaped plug according to an embodiment of the present invention.

[0034] Figure 4 This is a single module unit diagram of the upper unit component in an embodiment of the present invention.

[0035] Figure 5 This is a single module unit diagram of the upper unit component in an embodiment of the present invention.

[0036] Figure 6 This is a schematic diagram showing the positioning and alignment of the four module units of the upper module component.

[0037] Figure 7 This is a schematic diagram showing the positioning and alignment of the four module units of the lower module component in an embodiment of the present invention.

[0038] Figure 8 This is a schematic diagram of the upper module component in an embodiment of the present invention.

[0039] Figure 9 This is a schematic diagram of the lower module component in an embodiment of the present invention.

[0040] Figure 10 This is a schematic diagram of the overall structural connection in an embodiment of the present invention.

[0041] Figure 11 This is a hysteresis curve diagram of the connection node in an embodiment of the present invention.

[0042] Figure 12 This is a skeleton curve diagram of the connecting nodes in an embodiment of the present invention.

[0043] In the diagram: Module unit 1, Module column 11, Module beam 12, Upper column base plate 13, Lower column top plate 14, Node plate with cross-shaped plug 2, Cross-shaped plug 21, Cross-shaped plug connecting plate 22, High-strength bolt 3, Vertical connecting plate 4, Single-sided bolt 5. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Please see Figure 1 - Figure 8 The present invention provides a unit connection node for a steel structure modular building based on a cross-shaped plug, including a module unit 1, an upper column base plate 13, a lower column top plate 14, a node plate 2 with a cross-shaped plug, a high-strength bolt 3, a vertical connecting plate 4, and a single-sided bolt 5.

[0046] Module unit 1 is prefabricated in the factory, including: in the factory, module beams 12 are welded to adjacent sides of module columns 11; each module column 11 in the upper module assembly has an upper column base plate 13 fixed to its bottom; and each module column 11 in the lower module assembly has a lower column top plate 14 fixed to its top. Both the upper column base plate 13 and the lower column top plate 14 have cross-shaped holes for installing node plates 2 with cross-shaped inserts, improving installation accuracy and the strength of the node core area. The node plates 2 with cross-shaped inserts are prefabricated in the factory, including: in the factory, ten... The character-shaped plug 21 is welded onto the cross-shaped plug connecting plate 22 to form a node plate 2 with cross-shaped plugs. On-site, each module unit in the upper and lower module components is connected via single-sided bolts 5 and vertical connecting plates 4, forming a combined cross-section that shares the load, making it safer and more reliable. On-site, the upper and lower module components are connected as a whole using high-strength bolts 3 through the bolt mounting holes on the upper column base plate 13, lower column top plate 14, and node plate 2 with cross-shaped plugs, avoiding on-site welding and making installation efficient and convenient. This invention avoids on-site welding, ensures node construction quality, has a simple structure, clear force transmission, good mechanical properties, high strength in the node core area, and is easy to install.

[0047] In some embodiments of the present invention, the module unit 1 is prefabricated in the factory and includes: module column 11, module beam 12, upper column base plate 13 and lower column top plate 14. In the factory, the module beam 12 is welded to the adjacent two sides of the module column 11. At the same time, the upper column base plate 13 is welded to the column end of the upper module column 11, and the lower column top plate 14 is welded to the column end of the lower module column 11. A bolt mounting hole is reserved 2-5cm above (below) the welding part of the module column 11 and the module beam 12 for matching the bolt mounting hole on the vertical connecting plate, for installing a single-sided bolt 5.

[0048] In some embodiments of the present invention, the thickness te of the upper column base plate 13 and the lower column top plate 14 is greater than 8mm, and both the upper column base plate 13 and the lower column top plate 14 have cross-shaped holes, which are matched with cross-shaped inserts.

[0049] In some embodiments of the present invention, the node plate 2 with cross-shaped inserts is prefabricated in the factory and includes a cross-shaped insert 21 and a cross-shaped insert connecting plate 22. In the factory, the cross-shaped insert 21 and the cross-shaped insert connecting plate 22 are welded together to form the node plate 2 with cross-shaped inserts. The cross-shaped insert connecting plate 22 is provided with bolt mounting holes, and the ends of the cross-shaped insert 21 are chamfered for installation.

[0050] In some embodiments of the present invention, the upper and lower ends of the cross-shaped plug 21 are respectively inserted into the cross-shaped holes of the upper column base plate 13 and the lower column top plate 14, and the cross-shaped plug 21 plays the role of strengthening the core area of ​​the node; the high-strength bolt 3 matches the size of the bolt mounting holes of the cross-shaped plug connecting plate 22, the upper column base plate 13 and the lower column top plate 14.

[0051] On-site, each module column in the upper and lower module components is enclosed by single-sided bolts 5 and vertical connecting plates 4 to form a combined column, forming a combined cross section to share the load, which is safer and more reliable.

[0052] On-site, the upper and lower module components are connected as a whole by high-strength bolts 3 through the bolt mounting holes on the upper column base plate 13, the lower column top plate 14 and the node plate 2 with cross-shaped plugs, making the connection more reliable and simple.

[0053] In some embodiments of the present invention, the bolt mounting holes of the upper column base plate 13 and the lower column top plate 14 are standard holes or oblong holes to facilitate installation, and high-strength bolts 3 are selected.

[0054] In some embodiments of the present invention, the vertical connecting plate 4 is connected and fixed to the module column 11 by a single-sided bolt 5; and the thickness te of the vertical connecting plate 4 is greater than 8mm.

[0055] In some embodiments of the present invention, the module unit 1 of the upper module assembly and the lower module assembly, the node plate 2 with cross-shaped plug, the upper column base plate 13, the lower column top plate 14, and the vertical connecting plate 4 are all made of low-alloy high-strength structural steel Q355 steel; the high-strength bolt 3 and the single-sided bolt 5 are 10.9 grade bolts made of 20MnTiB.

[0056] The connection node provided in the foregoing embodiments of the present invention, in the field, involves four modular columns in both the upper and lower modular components being enclosed and fixed together by vertical connecting plates to form a combined column, creating a combined cross-section that shares the load, thus enhancing safety and reliability. In the field, the upper and lower modular components are connected by high-strength bolts, avoiding on-site welding and simplifying installation. This invention avoids on-site welding, ensures node construction quality, has a simple structure, clear force transmission, good mechanical properties, high strength in the node core area, and is easy to install.

[0057] The following is based on a finite force scenario:

[0058] I. Model Establishment.

[0059] The modular building connection nodes provided in the foregoing embodiments of the present invention were simulated using the large-scale general-purpose finite element software ANSYS 2022R2. The node models were established, and the geometric dimensions of the models are shown in Table 1.

[0060] Table 1. Geometric dimensions of model components, in mm.

[0061]

[0062] The steel used for the test specimens was all Q355B, with an elastic modulus of 206000 MPa, a Poisson's ratio of 0.3, and a density of 7.85 × 10⁻⁶. 3 kg / m 3 The stress-strain relationship was modeled using a bilinear model, as shown in Table 2. High-strength bolt 3 and single-sided bolt 5 were made of 20MnTi steel with a yield strength of 940 MPa, an elastic modulus of 206000 MPa, and a density of 7.85 × 10⁻⁶ MPa. 3 Kg / m 3 Poisson's ratio is taken as 0.3.

[0063] Table 2 Stress-strain parameters of Q355 steel

[0064] Key points stress Plastic strain Force stage 1 355 0 Elastic phase 2 470 0.0279 Strengthening phase

[0065] Quasi-static analysis was performed on the specimen model. To ensure calculation accuracy, all elements were selected as solid elements (Soild186), and the mesh at the connection points was refined. The welds of modular column 11, modular beam 12, and upper column base plate 13 (lower column top plate 14) were bonded together. Since the selected beam and column models were located at inflection points, hinged supports were set to simulate the boundary conditions at the inflection points of the column ends in the frame. The column base hinges only released rotational constraints within the specimen plane, while the column top hinges simultaneously released rotational constraints, horizontal and vertical translational constraints within the plane. This was achieved through analysis in ANSYS. Defining "contact pairs" allows for a more accurate simulation of the contact relationships between various components. The surface with higher stiffness is defined as the primary contact surface, and the surface with lower stiffness as the secondary contact surface. Frictional contact is defined between the upper column base plate 13, the lower column top plate 14, the node plate 2 with the cross-shaped insert, and the high-strength bolt 3. Frictional contact is also defined between the modular column 11, the vertical connecting plate 4, and the single-sided bolt 5. A modular model is used to simulate the frictional contact between the modular column 11, the upper column base plate 13, the lower column top plate 14, and the cross-shaped insert 21 in the modular connection node of this invention. The friction coefficient is set to 0.2. During calculation, the displacement degrees of freedom at the column ends are first coupled to prevent localized damage to the column during loading. Then, a static displacement load of 200mm reciprocating along the x-axis is applied at the column end coupling point according to the displacement mode, divided into 10 loading levels of 20mm each. Simultaneously, an 800kN vertical load is applied to the column top, controlling the axial compression ratio to be 0.12. High-strength bolt 3 and single-sided bolt 5 are made of M20 grade 10.9, with a preload of 155kN.

[0066] II. Results Analysis.

[0067] A cyclic reciprocating load was applied to the modular connection node of the present invention, and the hysteresis curve and skeleton curve of the node were obtained as follows. Figure 11 and Figure 12 As shown in the figure, yielding begins when the displacement control load reaches 40 mm, and the node ultimately fails mainly due to excessive plastic deformation in the nodal region. This type of node uses thin-walled components, which have good load-bearing capacity and seismic performance, conforming to the seismic performance-based design concept of "high load-bearing capacity - low ductility" in the "Steel Structure Design Standard".

[0068] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cross-shaped insert-based unit connection joint of a steel modular building, characterized by, The upper module assembly, the lower module assembly, the vertical connecting plate (4), the upper column bottom plate (13), the lower column top plate (14), the high-strength bolt (3) and the node plate (2) with a cross-shaped insert are included. The upper module assembly and the lower module assembly each include four module units (1), each of the module units (1) includes a module column (11) and a module beam (12) connected with the module column (11), and the four module columns (11) in the upper module assembly and the lower module assembly are each fixed to form a combined column by surrounding the vertical connecting plate (4). The bottom of each module column (11) in the upper module assembly is fixed with the upper column bottom plate (13), and the top of each module column (11) in the lower module assembly is fixed with the lower column top plate (14), and the upper column bottom plate (13) and the lower column top plate (14) are each provided with a cross-shaped hole and a bolt mounting hole outside the cross-shaped hole. The node plate (2) with a cross-shaped insert includes a cross-shaped insert connecting plate (22) and a cross-shaped insert (21) fixed on the cross-shaped insert connecting plate (22), the cross-shaped insert connecting plate (22) is provided with a bolt mounting hole, the upper and lower ends of the cross-shaped insert (21) are used for being inserted into the cross-shaped holes on the upper column bottom plate (13) and the lower column top plate (14) respectively, the cross-shaped insert (21) plays a role in strengthening the node core area, and the high-strength bolt (3) is matched with the bolt mounting holes on the upper column bottom plate (13), the lower column top plate (14) and the cross-shaped insert connecting plate (22).

2. A cross-shaped insert based unit connection joint of a steel modular building according to claim 1, characterized in that, A plurality of single-side bolts (5) are further included, and the vertical connecting plate (4) is connected and fixed with the module column (11) by the single-side bolt (5) in the upper module assembly and the lower module assembly.

3. A cross-shaped insert based unit connection joint of a steel modular building according to claim 1, characterized in that, The module unit (1) is prefabricated in a factory, the module beam (12) is welded on the two sides of the adjacent module column (11), the bottom end of each module column (11) in the upper module assembly is fixed with the upper column bottom plate (13), the top end of each module column (11) in the lower module assembly is fixed with the lower column top plate (14), and a bolt mounting hole for matching the bolt mounting hole on the vertical connecting plate (4) is reserved at 2-5 cm of the upper side or the lower side of the welding part between the module column (11) and the module beam (12).

4. A cross-shaped insert-based unit connection joint of a steel modular building according to claim 1, characterized in that, The thickness te of the upper column bottom plate (13) and the lower column top plate (14) is greater than 8 mm.

5. A cross-shaped insert-based unit connection joint of a steel modular building according to claim 1, characterized in that, The node plate (2) with a cross-shaped insert is prefabricated in a factory, wherein in the factory, the cross-shaped insert (21) and the cross-shaped insert connecting plate (22) are welded together to form the node plate (2) with a cross-shaped insert, and the cross-shaped insert connecting plate (22) is provided with a bolt mounting hole.

6. A cruciform plug based unit connection joint of a steel modular building according to claim 1, characterized in that, The end of the cross-shaped insert (21) is chamfered.

7. A cross-shaped insert-based unit connection joint of a steel modular building according to claim 1, characterized in that, The bolt mounting hole of the upper column bottom plate (13) and the lower column top plate (14) adopts a standard hole or an oblong hole to facilitate installation.

8. A cross-shaped insert based unit connection joint of a steel modular building according to any one of claims 1 - 7, characterized in that, The thickness te of the vertical connecting plate (4) is greater than 8 mm.

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